<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      typeof 'hello'; //string
      typeof function () {}; //function
      //....
      null; // object null

      typeof {}; // object
    </script>
  </body>
</html>
